The present invention relates to a method for manufacturing an example mesh sheet such as a latticed electrode for use in a battery and a manufacturing apparatus for carrying out the method.
As shown in FIG. 18, in an example mesh sheet, many strip-shaped lift portions (a) are connected with each other in a zigzag configuration by a latticed connecting portion (b). An apparatus for manufacturing such an example mesh sheet is proposed in Japanese Patent Publication No. 60-29573.
According to this conventional art, as shown in FIGS. 15(a) and 15(b), a plurality of slits (c) are intermittently formed on a strip (A) in the longitudinal direction thereof as the first process. In this stage, the slits (c) are arranged in parallel with each other on the strip (A) and the strip-shaped lift portion (a) is formed by the adjacent slits (c). At this time, the strip-shaped lift portions (a) adjacent to each other in the widthwise direction of the strip (A) are shaped by curvedly bend it in the direction opposite to each other and approximately in the thickness direction of the strip. A flat portion (d) is positioned widthwise in a belt-like configuration between the slits.
As shown in FIG. 17, the first process is carried out by a first roll (g) comprising a plurality of diskshaped cutters (f), having projections (e) provided at predetermined pitches in the periphery thereof, superimposed one on the other other at predetermined intervals and a second roll (h). Each strip-shaped lift portion (a) is pressed against the projection (e) approximately in the thickness direction of the strip and shaped by curvedly bend it between adjacent flat portions (d).
As shown in FIGS. 16(a) and 16(b), a slit (i) for connecting the adjacent slits (c) is formed in the flat portion (d) in the second process. The slit (i) is formed alternately-widthwise and formed in every other flat portion (d). The portion between the slits (i) adjacent to each other widthwise serves as the connecting portion (b).
The second process is performed by the second roll (h) and a third roll (j) as shown in FIG. 17. The third roll (j) comprises a plurality of disk-shaped cutters (k), having the projection (e) not formed thereon, superimposed one on the other and reliefs (1) are provided at predetermined pitches in the right and left sides alternately on both sides of the periphery of the disk-shaped cutter (k). Similarly, the relief (1) is provided on the disk-shaped cutter (f) of the second roll (h) and opposed to the relief (1) of the disk-shaped cutter (k).
In the third process, the strip (A) having the strip-shaped lift portion (a) and the connecting portion (b) formed thereon is extendably expanded widthwise as shown in FIG. 18.
However, the conventional art has the following issues:
1. Slits are formed in two processes and the use of two rolls are necessary for each process. Therefore, time-taking adjustments such as positioning between the two rolls and the rotating timing thereof are required to be made before starting a work, and there is a fear that a strip is cut two times.
It is necessary to use three kinds of disk-shaped cutters in the example shown in the drawings and in addition, the disk-shaped cutter of the roll used in both processes is consumed in a short time by a side pressure applied by the two rolls.
2. In shaping the strip, the strip-shaped lift portion is pressed by the top portion of the projection of the disk-shaped cutter and pulled in the rotational direction of the disk-shaped cutter, with the result that tensile stress concentrates on the rear portion of the strip-shaped lift portion. In the conventional manufacturing apparatus, as shown in FIG. 19, the projection (e) is longitudinally symmetrical with respect to a line, the top portion (m) thereof is positioned in the center in the rotational direction of the disk-shaped cutter, and the length of the rear portion of the strip is only half of the whole length of the strip-shaped lift portion (a). Therefore, the thickness of the rear portion of the strip is locally reduced and as such, the strip is likely to break when it is expanded.
3. According to the conventional apparatus, the relief (1) thicknesses of the disk-shaped cutters (f) and (j) are approximately the same in the base portion and peripheral portion thereof as shown in FIG. 20. Therefore, the disk-shaped cutter is likely to break in the base portion thereof. In particular, the disk-shaped cutter of the roll used in the two processes is likely to be damaged by the side pressure as described in item 1.
4. As shown in FIG. 21, with the expansion of the strip in the widthwise direction thereof, the connecting portions (b) adjacent to each other widthwise are separated from each other widthwise, with the result that first, the strip-shaped lift portion (a) is twisted, then, each connecting portion (b) rotates in the twist-removing direction. Thereafter, each strip-shaped lift portion (a) is bent with respect to the connecting portion (b) in the direction in which each strip-shaped lift portion (a) has been curved, with the result that the separation of the adjacent connecting portions (b) progresses.
As described above, according to the conventional art, the strip-shaped lift portion is twisted when an expanding starts. Therefore, a great force is required in the expanding operation, so that the longevity of an apparatus for the expanding operation becomes short.
This issue is outstanding when the thickness of the strip is large or a mesh is fine.